Originally Posted by Shawnc
Alright, so in my betta's 5g tank I have a few neon tetras, my betta is swimming at them and attacking them. I have no idea why I was told he wouldn't do that and I noticed that he didn't when I first got them. Also, when i turn on the light his face goes all black and he looks aggrivated. I have no idea what is causing this behaviour.
Neon Tetras prefer to be in schools of 10.(which in your current tank you do NOT have room for.)
I personally would return the neons.
Having them in smaller groups causes them to be insecure ,and thats when the fin nipping starts.
1-2 neon Tetras can and will shred your bettas tails to pieces.
With any unusual changes with my Betta, as soon as i notice i make a 25% water change to rule the environment out as as a cause of the behavior.